How C44300 Tube Sizes Are Specified
C44300 is the inhibited admiralty brass used for the majority of seawater condenser and heat exchanger tubes. Its size is never described by a single number: a complete specification combines outside diameter, wall thickness, length, temper, form and standard. Buyers who quote only the outside diameter frequently receive a tube that fits the tube sheet but fails on the thermal and pressure duty.
Under ASTM B111 and its metric companion ASTM B111M, tube is ordered as seamless, mandrel drawn product in the annealed temper, with dimensions stated either in inches or in millimetres. This article sets out the practical size envelope and the conventions that surround it.
Standard Size Ranges and Tolerances
| Parameter | Common range | Notes |
|---|---|---|
| Outside diameter | 0.250 in to 2.000 in, that is 6.35 mm to 50.8 mm | Larger diameters can be produced on request |
| Wall thickness | 0.028 in to 0.165 in, that is 0.71 mm to 4.19 mm | Usually ordered in Birmingham Wire Gauge |
| Most common gauge | 18 BWG, equal to 1.24 mm | Typical for power plant condensers |
| Length | Random 12 ft to 20 ft, or cut to length | Cut lengths are used for retubing projects |
| Form | Seamless, mandrel drawn | No longitudinal weld in the tube wall |
| Temper | Annealed, soft | Required for expanding, bending and rolling in |
Frequently requested combinations include 19.05 mm by 1.24 mm, 25.4 mm by 1.24 mm and 15.88 mm by 0.89 mm tube for condenser service, and heavier walls such as 2.11 mm or 2.77 mm for higher pressure or abrasive duties. Because the size conventions differ between markets, the purchase order should state the standard, the units and the gauge system explicitly.
Composition and Temper of the Tube
| Element | Weight % |
|---|---|
| Copper (Cu) | 69.0-71.0 |
| Tin (Sn) | 0.8-1.3 |
| Arsenic (As) | 0.03-0.06 |
| Lead (Pb) | 0.05 max |
| Iron (Fe) | 0.10 max |
| Zinc (Zn) | Balance |
| Total impurities | 0.30 max |
Density is approximately 8.53 g/cm³. Tube is delivered in the annealed condition so that it can be roller expanded into tube sheets, bent to the required radius and, in many designs, given a light flare. Harder tempers are available but reduce the amount of cold work the installer can apply at site.
Equivalent Standards and Grades
| System | Designation for admiralty brass tube |
|---|---|
| ASTM / ASME | ASTM B111 or ASME SB111, UNS C44300 |
| China | GB/T 8890, grade HSn70-1 |
| Germany | DIN 1785, CuZn28Sn1 |
| United Kingdom | BS 2871, CZ111 |
| Japan | JIS H3300, C4430 |
| Europe | EN 12451 for seamless copper alloy heat exchanger tube |
When a project is retubed, the existing tube sheet holes, the expansion procedure and the baffle spacing usually determine the size. Retubing therefore calls for close dimensional agreement, and a sample or a full dimensional report before shipment is good practice.
Ordering and Inspection Points
State the units and the gauge. A wall thickness of 0.049 in, 1.24 mm and 18 BWG describe the same tube; mixing them causes costly errors.
Check the tube sheet fit. Outside diameter tolerances are tight under ASTM B111 because expansion depends on the clearance between tube and hole. Oversized or undersized tube will not seal reliably.
Match the wall to the duty. Thicker walls raise pressure capacity and erosion life but reduce the heat transfer coefficient and increase bundle weight.
Confirm the temper. Soft tube is required for roller expansion. Verify hardness and tensile results on the mill test certificate before installation begins.
Expect non-destructive testing for critical service. Eddy current testing, hydrostatic testing and pneumatic testing can all be specified, together with a maximum depth of permissible surface defect.
Protect the surface. Tube ends are normally capped and bundles strapped onto wooden pallets; bright or clean bore surfaces simplify the expansion operation on site.
FAQ
Q: What is the most common C44300 condenser tube size?
18 BWG wall with an outside diameter of 19.05 mm or 25.4 mm is the workhorse combination for power plant and marine condensers, and 15.88 mm outside diameter with a 0.89 mm wall is common on smaller exchangers.
Q: How is wall thickness expressed?
Either directly in millimetres or inches, or in Birmingham Wire Gauge. For example 18 BWG equals 0.049 in or about 1.24 mm, so the gauge number must always be accompanied by the gauge system name.
Q: Is C44300 tube welded or seamless?
Heat exchanger tube to ASTM B111 is seamless and mandrel drawn. The absence of a longitudinal weld is important because the weld zone would be the first site of selective attack in seawater.
Q: Which temper should be ordered?
Annealed soft tube. It provides the elongation needed for roller expanding into the tube sheet and for bending, while still meeting the mechanical property requirements of ASTM B111 for the annealed temper.
Q: Can longer or shorter lengths be supplied?
Yes. Random lengths of 12 ft to 20 ft are standard, and cut-to-length tube is produced for retubing projects where the bundle geometry is already fixed.
Q: What tests should accompany a heat exchanger tube order?
Chemical analysis, tensile and hardness results, dimensional inspection, and where specified eddy current, hydrostatic or pneumatic testing. A mill test certificate listing all of these is the normal export document.
